Erosion Control March/April 2017 : Page 43

can get under the concrete channel bed liners and cause them to flip, allowing the water to directly impact the slope. The biggest issue is, if the channel fails, water will erode the soil and get into the trash. And with a heavy enough rain it could carry contaminants, and it could expose a creek to pollutants.” What Bowerman needed was a system to repair and reinforce the drainage channels that would be resilient to the unpredictable effects of differential settlement. Hanson says one of the worst things about the settlement issue is that “it just never stops.” He says that if the landfill operators made the decision to simply reline the ditches in the traditional manner, by merely filling the cracks with fresh concrete, it probably wouldn’t hold very long. “We were afraid we’d have to redo it in two years,” he says. And the cost would be high. Sjoquist, who is also the supplier of Concrete Cloth from Milliken Infrastructure Solutions, hosted a lunch-and-learn session on the product with Geosyntec, the civil engineer-ing firm providing management-consulting services to the Bowerman Landfill. Echoing Hanson’s concern, he says, “The thing with landfills is they are always sinking. The old way to deal with it was to use steel, concrete, and rebar to reline the drainage infrastructure.” However, he says, “Concrete Cloth’s compressive strength is three times that of Portland cement, and it can give under stress and meld to an area. If it does crack, it doesn’t crack all the way through, making it earth-quake resistant,” a quality of particular importance in Califor-nia. Furthermore, he says, because it is so economical, if it is disturbed by settlement, “we can do it again.” Repair Beats Replacement In addition to the cracking channels, says Sjoquist, Bowerman Landfill’s management was at a complete loss as to how to eco-nomically repair a collection of corroding stormwater drain-age pipes buried hundreds of feet within the landfill’s slopes. “Pulling those culverts out and replacing them would cost mil-lions of dollars, and to go in and try to re-sleeve them, which is the conventional way to repair a faulty underground fixture, is also very expensive,” he says. One additional complication: “These things curve a little bit as they go up the hills, and you have to have a perfectly straight shot for those slip tube pipe fix kits to work.” A few weeks after Sjoquist delivered the presentation on Concrete Cloth, Geosyntec invited him to meet and conduct a field demo for the landfill operators at a Caltrans site where the product was being deployed. After witnessing the easy installation, the landfill operators asked for a materials quote for the application at the Bowerman Landfill. During the subsequent bidding on the project, says Sjoquist, they were astonished when “the materials cost of using Concrete Cloth on the project came in at an estimate of about one-tenth of what they had expected to pay for just lining the culverts, with a much longer life expectancy.” He adds, “What we’re doing is saving them a ton of money on infrastructure.” The 420-foot-long concrete trapezoidal drainage chan-nels were re-veneered. After using a grout to fill in the cracks and voids that differential settlement had generated, explains Hanson, crews placed the Concrete Cloth over the existing www.roess-nature-group.de Beneﬁ t from our diverse capabilities and 100 years of experience Erosion-Control-Blanket-and Wattle Machines Conveyor Technology | Erosion-Control-Blankets | Erosion-Control-Nettings | Wattles | Biologs | Hydro-Seeding | Gabions | Subsurface Drainage | Subsurface Irrigation | Coir-Fiber Products | Coir Fiber Visit us at IECA 2017 in cooperation with since 1913 – Booth 301B MARCH/APRIL 2017 EROSION CONTROL 43